1. Field of the Invention
The present invention relates to a board-to-board connector.
2. Description of the Prior Art
A board-to-board connector is generally provided with a receptacle mounted on one of a pair of boards (e.g., a solid or flexible printed board) and a plug mounted on the other of the pair of boards (e.g., a solid or flexible printed board), wherein the receptacle and the plug are engaged with each other so as to be electrically connected to each other. The receptacle includes an insulator (receptacle insulator) made of synthetic resin and two arrays of receptacle contacts made of metal. The receptacle insulator includes two side wall, and the two arrays of receptacle contacts are symmetrically arranged to correspond to the two side walls of the receptacle insulator. The plug includes an insulator (plug insulator) made of synthetic resin and two arrays of plug contacts made of metal, similar to the receptacle. The plug insulator includes two insert side walls that are inserted between the two side walls of the receptacle insulator, and the two arrays of plug contacts are symmetrically arranged to correspond to the two insertion side walls of the plug insulator. Each receptacle contact includes an inverted U-shaped portion, a connecting leg portion and a U-shape-grooved continuity portion. The inverted U-shaped portion extends along the associated side wall of receptacle insulator, the connecting leg portion extends from one end of the inverted U-shaped portion outside of the associated side wall of receptacle insulator to be fixed to a conductive pattern formed on the associated board, and the U-shape-grooved continuity portion extends from the other end of the inverted U-shaped portion inside the associated side wall of receptacle insulator. The two arrays of plug contacts are supported by the two insert side walls of the plug insulator, respectively, and each plug contact includes a U-shaped continuity portion which is inserted into the U-shape-grooved continuity portion of the associated receptacle contact to establish electrical connection therewith, and a connecting leg portion which extends from the U-shaped continuity portion to be fixed to a conductive pattern formed on the associated board.
Inserting the two insert side walls of the plug insulator of the plug between the two side walls of the receptacle insulator of the receptacle causes the U-shaped continuity portion of each plug contact to enter the U-shaped groove of the U-shape-grooved continuity portion of the associated receptacle contact to thereby establish electrical connection between the U-shaped continuity portion and the U-shape-grooved continuity portion. Consequently, the aforementioned pair of boards (specifically the two arrays of plug contacts and the two arrays of receptacle contacts that are fixed to the pair of boards, respectively) are electrically connected to each other.
In this type of connector, the ease of inserting the plug into the receptacle has deteriorated as a result of the receptacle contacts and the plug contacts being miniaturized to the limit, the contact pitch being reduced to a minimum, the overall structure of the connector being miniaturized to the limit, and the height of the connector being reduced to a minimum. Furthermore, it is generally desired that only a small force be required when the plug is inserted into the receptacle and that a great force be required when the plug is extracted from the receptacle. However, it is an antimonic concept to achieve these two requirements at the same time.